1. Field of the Invention
The present invention relates to an image display device, a control method therefor, and an image display system.
2. Description of the Related Art
In recent years, in the progress of high definition of liquid crystal display devices, the level of user demand for the stability of display devices and the highly accurate color reproduction thereof also increases day by day. However, liquid crystal display devices will change in color reproducibility due to aged deterioration thereof. For that reason, in order for such liquid crystal display devices to achieve stable color reproducibility at all times, it is necessary to carry out calibration in a periodic manner.
In Japanese patent application laid-open No. 2002-209230, there is disclosed a processing method in which a patch for colorimetry or color measurement is displayed on a screen of an image display device, and adjustment of image quality is carried out by the measurement of the brightness and chromaticity of the patch by a user with the use of an optical sensor. Hereinafter, this processing method is referred to as calibration.
In addition, light emitting diodes (LEDs) have a long life span and are low in power consumption, so in recent years, they have been used as backlights for liquid crystal display devices. It is known that LEDs have their luminescence or emission properties changing in accordance with their temperature condition in which they are used. However, liquid crystal display devices are used under variety of environments, so there may be generated non-uniformity or irregularity in temperature for each of the LEDs (hereinafter referred to as temperature irregularity).
Moreover, in recent years, there is also known a control method which can obtain higher contrast by individually controlling the emission intensity for each LED according to an image signal inputted. (Hereinafter, this is referred to as local dimming.) Even in cases where local dimming is carried out, emission intensities of individual LEDs inside a backlight will vary according to the individual LEDs, and hence, temperature irregularity will similarly Occur.
When temperature irregularity occurs, the emission intensities of individual LEDs will vary for each LED due to the above-mentioned properties of the LEDs, as a result of which non-uniformity in brightness and chromaticity (hereinafter referred to as in-plane non-uniformity) will occur on a screen displayed on the liquid crystal display device. Thus, when calibration is carried out in a state where in-plane non-uniformity occurs in this manner, brightness and chromaticity will be different for each region in the screen, so it will be difficult to make adjustments with high accuracy.
In Japanese patent application laid-open No. 2008-147889, there is disclosed a processing method in which calibration can be carried out in a good manner even in cases where in-plane non-uniformity Occurs.
The processing method disclosed in Japanese patent application laid-open No. 2008-147889 is a method of measuring the in-plane non-uniformity of a display device, obtaining in-plane non-uniformity information, which is the result of the measurement, as well as information with respect to the position of display of a colorimetric or color measuring patch, and carrying out the adjustment of image quality by the use of both of these pieces of information.